Leg-mount caster.



G. E'. NEUBERTH. LEG MOUNT @ASTI-IR. .APPLIOMION FILED JAN. 15, 1909.

Patented Sept. 14, 1909.

nnrn s'rarns ana FFQFA.

GEORGE E. NEUBERTH, OF NEWARK, NEW JERSEY, ASSIGNOR TO UNIVERSAL CASTER85 FOUNDRY COMPANY, A CORLORATION OF NEW JERSEY.

LEG-MOUNT CASTER.

Specification of Letters Patent.

Patented Sept. f4, 1909.

' new and useful Improvements in Leg-Mount ufl Casters, (Case 4,) ofwhich the following 1s a specification, illustrated by drawings.

The invention was primarily made for brass and iron bedsteads havinghollow legs, but 1t is not limited thereto by its principles ofoperation. The forces at work in casters of this sort are analyzed tosome extent authoritatively in the circuit court opinion in UniversalCaster & Foundry Company against M. B. Schenck Company, reported inFederal Reporter, and it will not be necessary to review them in detail.

For hollow metal legs it has long been customary to have a terminalornamental enlargement or foot mount immediately above the caster.Several inventions, my own among others, are in use or known forcombining a leg mount with a caster for hollow legs, it being common tosupport the pintle, partially at least, against the interior of the legby various special means.

The present invention concerns primarily the leg mount, which, in thepreferred form of the invention is the sole and direct means of securingthe caster jaws and bearings to the leg mount, of supporting the leg,and of centering and holding in proper relationship to each other thevertical axis of the caster and the vert-ical axis of the leg.

A singlepreferred embodiment of the invention is shown in theaccompanying drawings. From this it will be apparent that some of thefeatures may be omitted with their individual functions withoutdestroying the utility of the caster as a whole though impairing protanto its mechanical perfection.

In the drawings Figure l is a side elevation, Fig. 2 a central verticalsection, and Fig. 3 a plan view of the combined leg mount and caster.Fig. 4 is a diagram of some of the forces at work when the leg andcaster are subjected to combined weight and side thrust.

The parts will be readily recognized and are lettered as follows: LegL,l leg mount M, spring retaining means therefor S, bearing balls B, pinor rivet P, caster jaws J, wheel W. The horizontal axis of the wheel Wis lettered A. The leg mount M is preferably of very simple design. Itenlarges downward from its point of contact with the exterior of the legat m through a graceful curve, turning inward at its base, as shown, andforming an inclining shoulder m which serves additionally to center theextreme end of the leg. At m it is dished to afford a ball race, and, ifdesired, a separate ball race R may be inserted over the balls B. Thepin P is preferably riveted rigidly at the axis of the leg mount and thejaws J swiveled upon the pin, the shoulders or enlarged head at thelower end of the pin serving to ret-.ain the jaws and the ball bearingsin place. The jaws are shown shaped to form the lower ball race, thoughobviously a separate race may be inserted. The split spring-retainingring S is flared at its upper margin for two reasons: Firstly, theflared portion prevents the spring ring from dropping out of the legmount when the leg mount is separate from the leg; and secondly, theflare provides a cam surface so that when the leg is thrust in the legmount it will expand the spring and pass freely in, causing the springto thereupon bind upon it and hold the caster to the leg.

It will be seen that primarily the weight of the leg and its load actaxially downward and are resisted by the upward supporting forcetransmitted to the jaws from the axle or axis of the wheel WV.Horizontal forces are produced by the dragging or movement of the legand caster upon the usual carpet or other friction-producing surface onthe floor. In addition to this last force, which results in a tiltingmoment in a vertical plane, there is a tilting moment acting in the samerotational sense by the eccentric position of the axis A from thevertical axis of the entire system whenever the horizontal movement ofthe leg causes the jaws to point in the reverse direction to thatmotion. Such is the case when the aws turn freely on their ball bearingsduring a rectilinear motion of the bedstead or other article offurniture.

It will be seen from Fig. 4 that the forces acting upward through theaxis of the wheel at A may act in a line that passes within or withoutthe extreme lower end of the periphery of the leg. In the latter caseonly will there be any considerable tendency to tip the leg mount, andthe force is so illustrated in Fig. 4. Such a tilting of the leg mounttends to occur primarily upon the lower end of the leg near the point min Fig. 4 and the leg mount tends to slide to the left. lf the shoulderm is present, as illustrated in all the figures, such sliding cannotoccur and consequently the tilting is checked by the uppermost point ofcontact of the leg mount at m against the smooth exterior surface of theleg. Neglecting friction, the force exerted on the leg mount at thepoint 'm is normal to the surface of the legand along the horizontalline shown in Fig. 4 leading from that point. As the forces along theline A ,c and m c intersectat the point c the third line of forcethrough the contact between the shoulder m and the leg must act upon theleg mount in the direction along the line c m. With the shoulder mpresent, therefore, if the length A c represents the force A c bycompleting the parallelograin we have the amounts as well as thedirections of the three forces represented by the lines A c, d c and c frespectively.V From this it will be evident that theshoulder at m may beformed by a conical surface which need be only steep enough to be normalto the line c f' to insure the proper centering of the leg mountnotwithstanding considerable varia.- tion and irregularity in theinterior margin of the foot of the leg. With the shoulder m absent,however, assuming that the force A c f acts through a line fallingoutside the foot f slipping will occur and the leg mount tend to tiltabout the point m of Fig. l t as a center until the other side of theleg mount swings downward into contact with@ of the leg,

the leg surface and stops the tilting. Under such conditions, therefore,the leg mount should nearly accurately fit the exterior of the leg andthe vertical distance between the points m m should be considerable andpreferably at least equal to or greater than the eccentricity of theaxis A as measured from the vertical axis of the leg and system. Moreusually, however, owing to the small amount of friction produced by aproper construction of caster wheel and by the ball bearings upon whichthe caster swivels, tilting will not occur because the force A c will bedirected inside of the lower extremity of the leg. In such case, in theabsence of a shoulder at m the leg can slip upon the leg mount only tothe extent necessary to bring it into contact with the side of the legmount that is toward the direction of the motion .of the leg.

I claim and desire to secure the following: l. A combined leg mount andcaster providing a hollow leg mount uponV which the' caster is directlysupported without cooperation betweenA its parts and the interiorsurfaces of the leg, and having frictional securing means separate fromsaid leg mount.

A combined leg mount and caster providing a hollow leg mount upon whichthe casterY is directly supported without cooperation between its partsand the interior surfaces of the VVleg, said leg mount having means forengaging the inner edge of the leg end for'the purposes setl forth. Y

3. A combined leg mount and caster providing a hollow leg mount uponwhich the caster is directly supported without cooperation between itsparts and the interior surfaces of the leg, said Aleg mount having aspring-holding means concealed within it and exterior to the leg. t

4. A combined leg mount and caster providing a hollow leg mount uponwhich the Ycaster is directly supported without coper spring-holdingmeans for engaging the legV mount and the leg when upon the leg. n

5. A combined leg mount and caster providing a hollow leg mount uponwhich the caster Vis directly supported without Vcooperation between itsparts and the interior surfaces of the leg, said leg mount. having meansengaging the inner edge of the leg end fork the purposes-set forth, said`legmount having' a spring holding means concealed within it andexterior to the leg. Y .l

G. A combined caster and leg mount in which the caster jaws are swiveledor secured directly to the leg mount and in which the leg mount extendsupward and is centered upon the exterior surface of the le' at adistance measured upward from the oot of the leg which substantiallyequals or exceeds t-he eccentricity of the caster Vwheelaxis, said legmount having means engaging the-inner edge of the leg-end for preventingside-slip of the leg upon the leg mount.

7. A combined caster and leg mount' in the eccentricity of the casterwheel axis, said Y leg mount having means engaging the inner edge of theleg-end for preventing side-slip of the leg upon the legmount and alsohaving means for frictionally engaging the cylindrical leg surface andholding the caster tothe leg. l i V d 8. A combined caster and leg mountin which the caster jaws are swiveled orsecured directly to the legmount and in which' the leg mount extends upward and is centered uponthe exterior surface of the leg at a distance measured upward from thefoot of the leg which substantially equals or exceeds the eccentricityof the caster wheel axis, and a spring holder within the leg mountembracing the leg when in place.

9. A combined leg mount and caster providing a leg mount adapted tosurround and be centered upon the exterior of the leg but enlargingdownward from its point or points of contact with the exterior of theleg, leaving a hollow or space between it and the leg, a caster swiveledto and supported on the leg mount, and spring means for directlysecuring the leg mount to the leg.

l0. A combined leg mountand caster providing a leg mount adapted tosurround and be centered upon the exterior of the leg but enlargingdownward from its point or points of contact with the exterior of theleg, leaving a hollow or space between it and the leg,

a caster swiveled to and supported on the leg mount, and spring meansfor directly securing lthe leg mount to the leg, said spring means beingwithin the said hollow or space.

l1. A combined leg mount and caster providing a leg mount adapted tosurround and be centered upon the exterior of the leg but enlargingdownward from its point or points of contact with the exterior of theleg, leaving a hollow or space between it and the leg, a caster swireledto and supported on the leg mount, and spring means for directlysecuring the leg mount to the leg, said spring means being loose withinthe said leg mount.

in testimony whereof I have signed this specilication in the presence oftwo subscribing witnesses; January 11th 1909.

GEORGE E. NEUBERTH.

Titnesses E. VAN ZANDT, M. M. RIEMANN.

